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Owing to low melting point (<100°C), negligible vapor pressure, and broad spectrum of applications, ionic liquids have gained much attention in the recent years. In this paper, the effects of temperature, polyvinyl pyrrolidone (PVP) polymer, and salts on the interfacial and bulk properties of aqueous solution of long-chain ionic liquid [i.e., 3-dodecyl-1-methyl-1H-imidazol-3-ium-bromide (C12mimBr)] were investigated using tensiometry. This long-chain ionic liquid was found to behave like a conventional surfactant, and thus it can be called surface active ionic liquid (SAIL). An inflection point in surface tension versus concentration curve at specific concentration was observed, which is termed the critical micelle concentration (CMC) of C12mimBr. The pre-micellar region was used to calculate various surface active parameters whereas the CMC was used to investigate its micellar behavior. Both surface activity and CMC of SAIL increased with the increase in temperature. No prominent effect was observed with the addition of PVP, whereas NaCl and CuNO3addition distinctly changed the CMC. Similarly, surface effectiveness (πcmc) of C12mimBr decreased with the addition of NaCl and increased with the addition of CuNO3, whereas addition of PVP showed no effect on it. It shows that PVP has negligible interaction with C12mimBr. Further, the process of micellization was found to be entropy driven. [ABSTRACT FROM AUTHOR]

This paper reports experimental values of dynamic viscosity for four binary systems of 1-ethyl-3-methylimidazolium tetrafluoroborate, [Emim][BF4], with dimethyl sulfoxide (DMSO), acetonitrile (ACN), ethylene glycol (EG) and 1,4-dioxane over the temperature ranges from 293.15 K to 353.15 K at p = 0.1 MPa. All binary mixtures were completely miscible over the entire range of mole fraction, except the system with 1,4-dioxane. The viscosity results have been correlated by the one parameter Grunberg–Nissan and Fang and He equations and the two-parameter McAllister, Eyring-UNIQUAC, Eyring-NRTL and Eyring-Wilson models and the results were compared. Additionally, the viscosity deviations, Δ η , and the excess Gibbs energy of activation for viscous flow, G ∗ E , were calculated and fitted to the Redlich–Kister equation. The results show that all Δ η values are negative over the whole composition range and the G ∗ E values are positive, except for the system with EG. The results of the excess functions are discussed in terms of molecular interactions. [ABSTRACT FROM AUTHOR]

A series of temperature-dependent gel-type ionic liquid compounds have been synthesized from 1-(3-sulfonic group) propyl-3-methyl imidazolium (abbreviated as MIMPS) and three vanadium-substituted heteropoly acids H5SiW11VO40, H5SiMo11VO40 and H7SiW9V3O40. The designed and synthesized gel-type polyoxometalate ionic liquids (POM-ILs) have demonstrated a tendency to exhibit a layered structure. Moreover, they can undergo a phase transformation from a viscous gel-state to a liquid-state below 100 °C, and ionic conductivity up to 10−3 S cm−1 was observed at 120 °C. Cyclic voltammetry was carried out to study their electrochemical properties in organic solutions, and it was found that the oxidizability of the three POM-ILs decreases in the order: [MIMPS]7SiW9V3O40 ＞ [MIMPS]5SiMo11VO40 ＞ [MIMPS]5SiW11VO40. This result indicates that the redox behavior can be tuned by changing the chemical composition of the heteropolyanions. [ABSTRACT FROM AUTHOR]

In this paper, a densimeter based on vibrating tube principle is used to determine experimentally the density of 1-butyl-2,3-dimethylimidazolium tris(pentafluoroethyl)trifluorophosphate and 1-butyl-2,3-dimethylimidazolium bis(trifluoromethylsulfonyl)imide at temperatures between (278.15 and 398.15) K and at pressures up to 120 MPa. The apparatus was calibrated by using water, vacuum and bromobenzene. The Tammann–Tait equation of state was used to correlate ( p , T , ρ ) results with standard deviations around 2 · 10 −4 g · cm −3 . Other volumetric properties, such as isothermal compressibility and isobaric thermal expansivity, were obtained from this equation. For each ionic liquid, the α p isotherms present a crossing point within the experimental pressure range. Besides, the effect that the C2-methylation in the imidazolium cation provokes on density values is analyzed. The prediction ability of the group contribution methods of Gardas and Coutinho and Jacquemin et al. were tested with the experimental densities. [ABSTRACT FROM AUTHOR]

In this work, two imidazolium-based ionic liquids 1-(2-aminoethyl)-1-dodecyl-2-methyl-4,5-dihydro-1H-imidazol-1-ium chloride ([ADMDI]Cl) and 1-(2-aminoethyl)-1-dodecyl-2-(trifluoromethyl)-4,5-dihydro-1H-imidazol-1-ium chloride ([ADTDI]Cl) were synthesized for the first time and their inhibitive effects on the corrosion of mild steel in 0.5 M HCl solution at elevated temperature were investigated by experimental and theoretical methods. The results of weight loss tests show the studied ionic liquids (ILs) can effectively retard the serious corrosion of mild steel and that the greatest efficiencies obtained at 368 K are 86.3% for [ADMDI]Cl and 92.7% for [ADTDI]Cl. Potentiodynamic polarization curves suggest those compounds act as cathodic-type inhibitors and that [ADTDI]Cl has the better inhibiting performance than [ADMDI]Cl, especially at low concentration. It is indicated by the study of scanning electron microscope (SEM) that both the surface morphology and the internal structure of mild steel samples are severely damaged by the corrosive environment at 368 K. However, such bad situation is greatly improved by using IL additives. The higher inhibition efficiency of fluoro-substituted IL proved by experimental results can be explained by theoretical studies. The data of quantum chemical calculations show the introduction of fluoro group can increase the amount of free electrons transferred from IL molecule to the vacant d-orbital of Fe atom and strengthen the dipole-dipole interaction between inhibitor and metal surface. Additionally, molecular dynamics simulations suggest [ADTDI]Cl has the higher adsorption energy than [ADMDI]Cl, which also confirms the better performance of the former as corrosion inhibitor for mild steel in acid environment at elevated temperature. [ABSTRACT FROM AUTHOR]

ABSTRACT We report the liquid crystalline (LC) assembly and lower critical solution temperature (LCST) properties of wedge-shaped block copolymer (BCP)/1-alkyl-3-methylimidazolium tetrafluoroborate ([C nMIM][BF4], n = 2, 4, 6) complexes ( 1- 3) depending on the alkyl chain length of the ionic liquids (ILs). In contrast to the crystalline BCP, all of the ionic samples showed LC phases. 1 with [C2MIM][BF4] exhibited a hexagonal columnar phase, and 3 with [C6MIM][BF4] exhibited a gyroid phase. Interestingly, a temperature-dependent transformation from columnar phase to gyroid phase was revealed for 2 with [C4MIM][BF4]. The phase difference may be explained by the supramolecular shape change that was dependent on the alkyl chain length of the ILs. The LCST behavior was characterized using the differential scanning calorimetry, turbidity observations, and the X-ray diffraction techniques. Notably, the primary d-spacing began to decrease at the clouding temperature ( Tc). 3 showed the highest Tc at 130 °C, which is greater than the temperature of the order-to-disorder transition. The results demonstrate that the subtle variation in the IL structure affects the morphological and LCST properties. © 2017 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2017, 55, 3587-3596 [ABSTRACT FROM AUTHOR]

The use of room temperature ionic liquids (ILs) as novel solvents in a range of industrial separation processes has received tremendous attention and research. Here, we investigate the potential application of ILs to remove the wastewater contaminants atenolol and atrazine. Specifically, using molecular simulation we predict IL/water partition coefficients of atenolol and atrazine in seven common 1-n-butyl-3-methylimidazolium based ILs and investigate the underlying structural details. We find that atenolol and atrazine have a large affinity for the ILs over water. With a solute mole fraction of 0.1, the IL characteristic structure is virtually unchanged, suggesting ILs are able to accommodate the solutes well. Additionally, we demonstrate that within an IL, the solute affinity for the IL can be greatly improved by selecting an anion and/or cation that interacts strongly with the solute. [ABSTRACT FROM PUBLISHER]

Surface properties for three binary mixtures containing a 1-butyl-3-methylimidazolium thiocyanate ([BMIM][SCN]) and a long-chain alcohol (1-butanol, 1-pentanol and 1-hexanol) were determined by surface tension data at the following temperatures: (298.15, 308.15, 318.15, 328.15 and 338.15) K. The surface tension data over the entire mole fraction range are correlated by the Fuet al.(FLW) and Myers-Scott (MS) models. There is good agreement between the experimental data and the results of correlations for 15 binary systems (the three systems at five temperatures) with an average relative error below 1.5%. In addition, the UNIFAC group contribution method is applied for calculation of activity coefficients of components in solution. Moreover, the relative adsorptions of alcohol at the air/liquid interface are determined using Gibbs adsorption isotherm. The obtained results show that the values of adsorption for mixtures of alcohols/[BMIM][SCN] increase with increasing the alkyl chain length of alcohol and decreasing temperature. [ABSTRACT FROM AUTHOR]